1. Field of the Invention
The present invention relates to a pipe joint.
2. Description of Related Art
A pipe joint that connects a rubber tube and a metal pipe has been known. For instance, JP 11-311384A, JP 4-18791U, JP 5-1793A and JP 2007-321857A teach a technique of the pipe joint provided with a corrugated surface, which has a plurality of annular grooves and annular projects at an outer peripheral wall surface of the metal pipe. In the pipe joint, the metal pipe is radially inwardly inserted and placed in the rubber tube, and a metal sleeve is placed outside of the rubber tube. Furthermore, the rubber tube is pressed and fitted to the corrugated surface in a manner where a small diameter portion, i.e., a pressed portion, is provided by deforming the sleeve radially inside. In the above structure, it is limited that the rubber tube is separated from the metal pipe, by the combination of the corrugated surface of the metal tube and the small diameter portion of the sleeve.
According to the conventional structure, the sleeve has one or more small diameter portions. The small diameter portions are only located radially outside of the corrugated surface, since the small diameter portions are provided to press the rubber tube to the corrugated surface.
However, in the conventional structure, the corrugated surface is formed adjacent to an end portion of the metal pipe. Therefore, stress concentration may occur at the rubber tube of the end portion of the metal pipe.
Specifically, in a case of the pipe joint recited in JP 2007-321857A, the stress concentration may occur in the rubber tube at the end portion of the metal pipe, since the small diameter portion of the sleeve is placed adjacent to the end portion of the metal pipe.
Furthermore, in JP 11-311384A and JP 4-18791 U, a straight pipe portion that has a predetermined length is formed at the end portion of the metal pipe. However, in the above described structure, the body size of a pipe joint will possibly be large.